JPH0497813A - Ejector speed control apparatus of injection molding machine - Google Patents

Abstract

PURPOSE:To utilize the capacity of an electromotor to the max. degree by issuing a command setting the current flowing to the electromotor on the basis of the deviation of the speed command generated by a speed controller and the speed detected by a speed detector. CONSTITUTION:A position pattern generating apparatus 51 for generating the command of the position of an ejector at each point of time is provided. A speed command is generated on the basis of the position patterns generated from the position pattern generating apparatus 51. Further, an objective position and objective speed are set and the speed is integrated to obtain a position command. At first, an electromotor 31 is subjected to lamp accelerating at the possible max. acceleration. When the position command due to a position detector 60 reaches 1/2 of the objective position before the electromotor reaches the objective speed, lamp deceleration is performed. Contrarily, when the electromotor reaches the objective speed before the position command reaches 1/2 of the objective position, acceleration is stopped and the electromotor is driven at the objective speed until the position command reaches 1/2 of the objective position. At this time, the time during this period is measured and, continuously, the electromotor is driven at the objective speed until the same time is elapsed and, thereafter, lamp deceleration is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ejector speed control device for an injection molding machine.

(Prior art) Conventionally, resin heated and fluidized in a heating cylinder is injected into a mold under high pressure, cooled and atomized or hardened therein, and then the mold is opened to take out the molded product. In such an injection molding machine, a mold clamping device is provided opposite to the injection device, and the movable platen is moved toward and away from the fixed platen by the mold clamping device.

Further, a movable mold and a fixed mold are disposed on the movable platen and the fixed platen, respectively, and molten resin is injected from a nozzle of an injection device into a cavity formed between the two to perform molding. When cooling in the pressure holding step is completed, the mold is opened with the molded product remaining on the movable side, and the molded product is ejected from the mold by an ejector device.

As injection molding machines change from hydraulic type to electric type, servo ejector type ejector devices are increasingly being adopted. In this case, since the ejector is driven by an electric motor, stopping accuracy, repeatability, etc. are significantly improved compared to conventional hydraulic ejectors.

FIG. 5 is a diagram showing a conventional ejector device.

Reference numeral 1 denotes a movable platen, which moves in the left-right direction in the figure by a mold clamping toggle link (not shown) and connects the movable mold 2 and the molded product piece 3 fixed to the movable mold 2 to a fixed mold (not shown). It is designed to let you go. Therefore, the movable mold 2 is fixed to the movable platen l via a movable mounting plate 4 and a spacer block 5.

Then, the resin injected from the nozzle passes from the sprue through the runner and fills the cavity 6 formed between the fixed mold and the movable mold 2.

When the above injection process is completed, a pressure holding process is started in which the pressure inside the cavity 6 is increased, cooling of the resin is started, and after a certain period of time, both molds are moved with the molded product left on the movable mold 2 side. is opened and the molded part is ejected by the ejector device.

Therefore, an ejector pin 7 is provided that penetrates the movable mold 2 and the molded product block 3 in a movable portion to the left and right in the figure. The ejector bin 7 has one end in contact with the molded product, and
It has a flange lO at the other end, and a first ejector plate 8 and a second ejector plate 9 are provided so as to surround the flange lO.

The first ejector plate 8 is disposed adjacent to the movable side mounting plate 4, and is supported so as to be movable in the two directions of the movable mold. When the first ejector plate 8 moves to the right in the figure, the ejector bin 7 moves accordingly. It is designed to move to the right.

In the ejector device having the above configuration, when the device is driven by an electric motor, an ejector rod 11 is provided on the left side of the first ejector plate 8 for pushing the ejector plate 8 in the right direction. The ejector rod 11 has a ball screw formed on its surface and extends through a rotatably supported ball nut 12. By rotating the ball nand 12 with an electric motor, the ejector rod 11 is moved from side to side.

In the ejector device as described above, the ejector is This position control pattern occurs as follows.

FIG. 6 is a diagram showing an ejector pattern in an ejector speed control device for an injection molding machine.

This method is used in NC devices of machine tools, etc., and when applied to the ejector speed control device of an injection molding machine, the ejector target speed and the target position of the ejector protrusion position are given, and the ejector target is set according to these target values. Calculate the time it takes to reach the target position with an ejector protrusion value of 1 when the ejector is raised in steps at a speed.

That is, a first-order lag filter with a time constant is applied to the ejector target speed A to enable the electric motor to respond. At this time, a target speed as shown by B is obtained. The target position can be obtained by integrating the target achievement level B after passing through this -order filter.

According to this method, the ejector speed can be increased to the target speed, and the target value 1 of the ejector protrusion position can be accurately calculated.

(Problem B to be Solved by the Invention) However, in the conventional ejector speed control device for an injection molding machine, the performance of the electric motor cannot be fully utilized, and the control for pattern generation becomes complicated.
This increases the load on the computer.

Furthermore, as shown in the target speed B after passing through the first-order filter in Fig. 6, at the target speed obtained by passing the first-order lag through the step-like target speed, a considerably large acceleration is required to start up the speed, but the electric motor Due to torque limitations, the time constant of the -order lag must be increased. In this case, the rise time becomes longer and the ejector ejection cycle has to be lengthened.

The present invention solves the problems of the ejector speed control device of the conventional injection molding machine, maximizes the performance of the electric motor, and uses a simple algorithm to avoid prolonging the ejector ejection cycle. It is an object of the present invention to provide an ejector speed control device for an injection molding machine in which the actual final position does not differ from the actual final position obtained by integrating the target speed.

(Means for Solving the Problems) For this purpose, the ejector speed control device for an injection molding machine of the present invention includes a position pattern generation device for generating commands for the position of the ejector at each point in time, and the position pattern generation device a speed controller that generates a speed command from the deviation between the position pattern generated by the position pattern and the position detected by the position detector, and a differential value of the position pattern; and a speed command generated by the speed controller and the speed detector that detects the speed command. a current controller that commands Na to flow through the motor based on the deviation from the speed determined by the motor; a means for setting the target position and target speed; a means for obtaining a position command by integrating the speed; and a ramp at the maximum acceleration that can accelerate the motor. means for performing ramp deceleration when the position command reaches the target position 172 before reaching the target speed; and means for performing ramp deceleration when the position command reaches the target speed before reaching the target position 172; The motor is stopped and driven at the target speed until the position command reaches the target position 172, and the time T during that time is measured.Then, the motor is driven at the target speed until the same time T has elapsed, and then ramp deceleration is performed. I try to have the means.

(Function) According to the present invention, as described above, a position pattern generation device for generating the ejector digit 1 command at each point in time is provided, and the position pattern generated by the position pattern generation device and the position detection are A speed controller generates a speed command from the deviation from the position detected by the device and the differential value of the position pattern.

A TL flow to be supplied to the electric motor is commanded based on the deviation between the speed command generated by the speed controller and the speed detected by the speed detector.

Also, target value! and means for setting a target speed, and means for obtaining a position command by integrating the speed.

Then, the electric motor is first ramp-accelerated at the maximum acceleration possible, and when the position command reaches 1/2 of the target position before reaching the target speed, ramp deceleration is performed, and conversely, the position command is 1/2 of the target position. If the target speed is reached before reaching the target position, the Karo speed is stopped and the position command is set to 1. of the target position. /2
Drive at the target speed until the target speed is reached. At this time, the time T during that time is measured, and then the vehicle is driven at the target speed until the same time T has elapsed, and then ramp deceleration is performed.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 2 is a schematic diagram of an ejector control device for an injection molding machine showing an embodiment of the present invention.

In the figure, 21 is a first ejector plate to which an ejector pin (not shown) is fixed and for moving the ejector bin to the right in the figure.

facing the second ejector plate 21 at a predetermined interval S
An ejector lot 22 is disposed at the end.

A ball screw 23 is formed around the ejector rod 22, and extends through the ball nut 24. The ball nut 24 has a boot IJ25 on the outer periphery.
A timing heald 27 is stretched between the pulleys 25 and 26.

The pulley 26 is rotated by an electric motor 31, and an encoder 32 attached to the electric motor 31 detects the absolute position of the ejector rod 22.

Further, there is a certain distance S between the ejector port and the tip of the door 22. A detector 33 for detecting that the distance S between the ejector plate 21 and the ejector plate 21 has become smaller than
will be placed.

When replacing the mold or turning on the power and starting up the injection molding machine, the electric motor 31 is initially rotated at low speed.
The ejector rod 22 moves forward, but the distance! The detector 33 is arranged so that the MS becomes short and the detector 33 is turned on. The encoder 32 reads the position 1 at this time, and stores it in the controller of the injection molding machine as the position at which the ejector rod 22 starts ejecting, that is, the origin.

The origin determined by this step (calibration) is the starting position of the ejection operation for each cycle.

Next, the operation of the ejector speed control device of the injection molding machine having the above configuration will be explained.

First, the pulley 26 is rotated by the electric motor 1a31. This rotation is transmitted to the pulley 25 via the timing heald 27, and the pole nut 24 mechanically coupled to the pulley 25 rotates, causing the ball screw 23 to move back and forth.

When the ejector rod 22 attached to the tip of the ball screw 23 moves forward, it pushes the first ejector plate 21 and ejects the molded product.

FIG. 1 is a block diagram of an ejector speed control device for an injection molding machine according to the present invention.

In the figure, 51 is a position pattern generator, 52 is a differentiator, 53 is a position system, and 54 L is a speed system 711.
Xi, 55ha current system? 11 devices, 56 is an inverter device,
57 is a current sensor, 31 is an electric motor, 59 is a speed detector, and 60 is a position detector.

In the ejector speed control device for an injection molding machine configured as described above, the position pattern generated by the position pattern generator 51 and the position detected by the position detector 60 are compared, and the deviation thereof is input to the position controller 53. The output of the position controller 53 and the output of the position pattern passed through the differentiator 52 are added in a feedforward manner and compared with the speed detected by the speed detector 59, and the deviation is sent to the speed controller 54. is input.

And the output of the speed control J11H54 is electric 1!13
The current flowing through the current sensor 57 is compared with the output from the current sensor 57, and the deviation is input to the current controller 55.
The output is manually input to the inverter device 56.

The second control device controls the position of the electric motor 31 according to the position pattern generated by the position pattern generator 51.

Here, it is difficult to generate the above-mentioned position pattern, and if a position pattern is generated that does not allow acceleration taking into account the inertia of the electric motor 31, pulleys 25, 26, ball screw 23, etc., the electric motor 31 will follow the position pattern. The molding cycle of the injection molding machine will be interrupted and the molded product will be adversely affected.

Furthermore, if the position pattern is too slow, the ejector protrusion and return cycle becomes too long, which lengthens the molding cycle and reduces productivity.

Therefore, in consideration of the torque of the electric motor 1!31 and the load inner/middle, a position pattern is generated that places less burden on the CPU etc. and allows acceleration at the maximum possible acceleration.

Next, a procedure for generating a position pattern in the ejector speed control device for an injection molding machine according to the present invention will be described.

Figure 3 shows the ejector speed control 111 of the injection molding machine of the present invention.
FIG. 4 is an operation flowchart of position pattern generation in the ejector speed control device of the injection molding machine of the present invention.

Step S1 Make initial settings. Target position S. and target speed v0, and set the timer to T=0, speed command v=Q, and position command p=o.

Step 7 S2, 53 Position command ρ is 1 of target value WS0
pulley 25. until it reaches 72. -26, ball screw 2
3. Considering the inertia of the electric motor 31, etc., ramp acceleration is performed at the maximum acceleration that can be accelerated by the electric motor 31.

When the position command p obtained by integrating the speed during this period reaches 1/2 of the target position S0, the process advances to step S9,
As shown in FIG. 3b, the vehicle decelerates at the same acceleration as during ramp acceleration.

Steps 54 to S8 As shown in the third section a, 1 of the target position is reached during ramp acceleration at the maximum acceleration.
When the speed command V reaches the target speed v0 before reaching /2, the ramp acceleration is stopped and the command is given as a constant speed.

At this time, a timer is activated to start counting T. Thereafter, when the position obtained by integrating the speed from the time of startup reaches 1/2 of the target position, counting of T is stopped and the value of T starts to be subtracted.

Step 59 ~ Sll When the value of T above becomes 0,
Start ramp deceleration. Then, when the speed value reaches O, generation of the position pattern is stopped.

With the simple algorithm described above, the ability of the electric motor can be utilized to its maximum potential.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described in detail above, according to the present invention C=, a position pattern generation device for generating commands for the position of the ejector at each point in time is provided, and the position pattern generation device generates A speed command is generated based on the position pattern.

The motor also has a means for setting a target position and a target speed, and a means for obtaining a position command by integrating the speed. When the command reaches 1/2 of the target position,
Ramp deceleration is performed, and conversely, the position command becomes 1/2 of the target position.
If the target speed is reached before reaching 172, the acceleration is stopped and the position command is driven at the target speed until it reaches the target position 172. At this time, the time T in between is measured, and then the same time T The vehicle is driven at the target speed until the time period elapses, and then ramp deceleration is performed.

Therefore, a position pattern can be generated using a simple algorithm, and the performance of the electric motor can be utilized to the maximum.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ejector speed control device for an injection molding machine according to the present invention, FIG. 2 is a schematic diagram of an ejector control device for an injection molding machine showing an embodiment of the present invention, and FIG. 3 is a block diagram of an ejector speed control device for an injection molding machine according to the present invention. FIG. 4 is a time chart of position pattern generation in the ejector speed control device of the injection molding machine of the present invention. FIG. Figure 6V is a diagram showing an ejector pattern in an ejector speed control device of an injection molding machine. 3! - Electric motor, 51...Position pattern generator, 52
...Differentiator, 53 Position controller, 54...Speed control l
device, 55... current controller, 56 inverter device, 5
7... Current sensor, 59... Speed detector, 60...
・Position detector. Thorn patent applicant Sumitomo Heavy Industries, Ltd. sub-agent Patent attorney Makoto Kawai (1 other person) Figure Figure Figure

Claims (1)

[Claims] (a) A position pattern generator for generating commands for the position of the ejector at each point in time; (b) A position pattern generated by the position pattern generator and a position detected by a position detector; (c) a speed controller that generates a speed command from the differential value of the position pattern; (d) means for setting a target position and target speed; (e) means for obtaining a position command by integrating the speed; and (f) a ramp at the maximum acceleration that can accelerate the motor. (g) means for performing ramp deceleration when the position command reaches 1/2 of the target position before reaching the target speed; (h)
When the target speed is reached before the position command reaches 1/2 of the target position, acceleration is stopped and the position command reaches 1/2 of the target position.
The injection method is characterized by having means for driving at the target speed until reaching /2 and measuring the time T during that time, then driving at the target speed until the same time T has elapsed, and then ramping deceleration. Molding machine ejector speed control device.